Tom,
Too may variables to give you a solid equation but here is some info that might help. A few first things gathering from what we already know from Technology Associates. 1. You have a history to go on. 2. Product is low-cost high-volume. 3. Process and equipment perfected. 4. Distribution channels already in place.
In the current economy 2 methods are generally used. Either 3-7x annual net (3-4 is common, higher multipliers for short life, high profit, usually high tech ventures) OR 1X Gross. As long as you are making at least 20-25% you should find that these numbers are close.
How to determine the multiplier. With this product you have to look at practical life of the product. The easiest way to figure this out is to work the buyers scenario backwards. Lets take an example that has nothing to do with your company.
A product has a history of 20% annual net, a volume of $100K/yr, expected lifetime of 5 yrs. A buyer will want to pay off the price of the product line in 3.5 yrs. So $70K to buy the rights to the product is good for the buyer. In this example it's simple to figure out multiplier of 3.5
Now add to this simple example your history of growth, per year, projected out as far as the life of the product, startup manufacturing cost or lack of it if equipment is part of the sale, current inventory, supplier contact info, R&D, Distribution, resale value of the product rights at the end of its projected life, etc and you will come out with a figure.
Now the interesting part. If selling the product line ever comes up. Simply put, you want a buyer with alot of ego. You want a buyer that thinks he can do it alot better than you can. Draw your conclusion from that statement and you'll see why.
Please feel free to contact me if you have any questions.
Best regards,
Randy